POISONOUS SNAKES OF Some snakes lay eggs and others produce the youn2; alive. There is about an even
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Transcript of POISONOUS SNAKES OF Some snakes lay eggs and others produce the youn2; alive. There is about an even
Robert F. Clarke
Department of Biology
Kansas State Teachers College of Emporia
THE KANSAS SCHOOL NATURALIST
Vol. 5 February
No. 3 1959
The Kansas State Teachers College of Emporia
Prepared and Issued by
The Department of Biology, with
the cooperation of the Division of Educatioll
Editor: John Breukelman
Department of Biology
Editorial C01nmittee: Ina M. Borman, Robert F. Clarke,
Helen M. Douglass, Gilbert A. Leisman, Carl W. Prophet,
Because of the greatly increased cost, due to the color plates, no free copies of this issue will be available. Extra copies may be obtain ed for 25 cents each, postpaid. Send orders to The Kansas School Naturalist, Department of Biology, State Teachers College, Emporia, Kansas.
The Kansas School Naturalist is sent upon request, free of charge, to Kansas teachers and others interested in nature education.
The Kansas School Naturalist is published in October, December, February, and April of each year by The Kansas State Teachers Col lege, Twelfth Avenue and Commercial Street, Emporia, Kansas. Second-class mail privileges authorized at Emporia, Kansas .
Poisonous Snakes of Kansas by Robert F. Clarke
Many persons either do not know anything
The prime reason that every per son should know the poisonous snakes of his region by sight and know something about their habits, distribution, and abundance is that it will ease the mind of the average individual in all of his outdoor pur suits . :vlost persons have heard so many false stories about snakes that they develop a fear of all snakes. This fear is tmfOHnded! A person who knows what poisonous snakes he can expect to encounter in a given area need only learn to identi tv these and realize that all other s'nakes , lizaords , frogs, toads , sala manders , and turtles do not have a poisonous bite, and, therefore, he nee d not fear them. vVith a knowledge of the poisonous snakes, a persoll can avoid places where these snakes might be found. An other aspect is the conservation of snakes. Too many people kill snakes just because they happen to be snakes. This IS uncalled for destruc tion-a non-poisonous snake should no more be killed than a song bird. In many cases, the harmless snakes are of direct economic value.
In generc;.l, all snakes are similar i:1 habits. In Kansas, they retire for the winter in places where the lemp~rature will not get below the freezmg point. These may be in rJcky ledges, beneath the soil, be l ~ w the roots of trees, or in pro lecteJ places of human design, such as grc: in bins, cisterns, cellars, and silos. With the warm days of spring, the snakes emerge from their win ter quarters and set about finding food and mates. After mating, the sexes separate and each individual snake goes its own wa), to forage fer food for the rest of the year. Some snakes lay eggs and others produce the youn2; alive. There is about an even division of these types in Kansas. The king snakes, rz. t snakes, bull snakes, racers , and many smaller snakes lay eggs in early summer. These eggs are de posited in a spot suitable for hatch ing, generally beneath a rock or in the soil. When thev hatch, the young fend for thems~lves. In Kan sas, water snakes, garter snakes, poisonous snakes, and some smaller sT'.akes give birth to living young in bte summer or early fall. Again, the young are OIl their own after birth. With the coming of cooler weather, the snakes leave their summer feeding grounds and travel to phces where they will hibernate for the winter.
MYTHS: Probably no other group of animals has had the variety and expanse of tall tales credited to them as have the snakes. As the stories go , there are snakes
that can put their tHils in their mouths and roll downhill hoop-like, snakes that are capable of milking cows dry, snakes that fly into pieces when struck and later reassemble into whole snakes again , snakes that charm their prey, and others too numerous to mention here. Some of these tales deal specifically with the pois onOllS power of snakes or with snakes that are venomous. There is the "Blow viper," whose very breath is poionous! The butt of this fable is the utterly harmless hog nosed snake, pictured on Page 13. Many persons think that the poisonous "fang" of a snake is the structure which is fre quently flicked in and out of the snake's mouth. This is really its tongue, and is present in all snakes. The "fang" is an en larged tooth in the upper jaw (see dia gram, page 5). Four of the many un truths about poisonolls snakes are (1) rattlesnakes cannot cross a horsehair rope-they can! (2) cottonmouth water moccasins cannot bite under water they can! (3) rattlesnakes always rattle before they strike-not always! (4) the rattles present on the tail of a rattlesnake indicate the snake's age-no, a new seg ment is added each time that the skin is shed, which may occur several times dur ing a year.
FOOD: Most of the adult poisonous snakes of Kansas consume only warm blooded prey, consisting primarily of small rodents: white-footed mice, shrews, voles, and cotton rats in the fields, and house mice and rats about human habi tations. Small birds and young rabbits may be taken, as well as occasional liz ards and insects. The copperhead is more insectivorous than the rattlesnakes, and the cottonmouth feeds upon other crea tures that inhabit the edges of waterways.
The poison of venomous snakes is not only a defensive mechanism, but also a highly efficient food-getting device. Whereas some of the snakes strike and hold the prey within their jaws until the
poison has rendered it helpless, others only strike and follow the trail to where the victim falls.
In feeding, the snake does not chew its food, but swallows it whole. The jaws are wonderfully adapted for this purpose, having the bones on each side of the jaws attached to their mates on the other side by an elastic ligament, and the upper and lower jaws also joined by such an attach ment. This allows the jaws to be spread apart and lowered , making an opening capable of taking in a food item actually larger in diameter than the snake! The teeth of both the upper and lower jaws are recurved, pointing inward, and a5 each section of the jaw can work inde pendently, one side secures its grip while the other side moves forward. Thus, the snake actually crawls around its food.
ABUNDANCE: The non-p 0 ion 0 u s snakes far outnumber the poisonous kinds, both in number of species and in dividuals. In the United States, there are approximately 95 species of non poisonous snakes and only 19 species of poisonous ones, including 15 rattlesnakes, one copperhead, one cottonmouth, and two coral snakes. In Kansas, there are six species of poisonous snakes (two should hardly be counted) and 34 species of non-poisonous snakes. Many of the non poisonous species are common and wide spread. It is far more probable that any snake seen is non-poisonous than poisonous.
SNAKE BITE: Venom is secreted from glands within the head, on each side be hind the eyes, causing the swollen ap pearance of the head in this region. The venom travels through ducts to each of the two fangs. The fangs are enlarged teeth in the front of the upper jaw. They are hollow, with one end connected to the poison duct and the other end having an opening on the front edge near the tip. The fangs are also fastened to a moveable hone, which enables the fangs to be
folded back against the upper jaw when the mouth is shut and erected and di rected forward when the mouth is opened to strike. The po\ver of a strike imbeds the fangs into the skin of the victim, and muscles force venom from the glands through the duct and hollow fang and out of the opening at the tip. The venom causes a breakdown of the red blood corpuscles and walls of blood vessels. It also has an effect upon the nervous system. Some snakes have venom which is much more destructive to the nervou~ system. The pit vipers have venom which is more he111otoxic (destructive to blood) , whereas the coral snake, which belongs to the cobra group, has a venom which is neurotoxic (destructive to nerves).
The venom is yellowish and somewhat "thicker" than water. The amount of poison ejected at anyone strike varies from a part of a drop to 2 cubic centi meters, depending upon size and kind of snake, and time elapsed since last venom ejection. Various factors influence the amount of venom which is injected into the victim, i.e. , smaller snakes have smaller fangs and less venom; strikes through clothing or footwear are less ef fective.
It has been estimated that there are fewer than 50 deaths due to snake bite in the United States in a year ; most of these bites result from imprudent hcmdling of venomous serpents. There has been no survey of snakebite in Kansas, but few deaths are reported annually. At times several years have elapsed without any deaths being reported. Most victims are less than 20 years of age and most bites occur on the hands, feet, arms, or legs.
It should be stressed that poisonous snakes cannot be made harmless by re moving the fangs. The poison glands and ducts remain and other teeth can still scratch the skin, allowing entranc